Magnesia brick has been widely used as lining material because it has a high melting point and superior resistance to corrosion caused by a basic slag. Magnesia brick however is not resistant to structural spalling, and therefore there has been proposed magnesia-chrome brick in order to prevent the break-up caused by structural spalling. The major raw materials of magnesia-chrome brick are magnesia material and chromite. Magnesia-chrome brick is very resistant to corrosion and heat spalling in addition to structural spalling.
In recent years, it has been reported that the intake, inhalation or contact with large amounts of chrome causes a human body rhinitis, dermatitis, bronchitis etc. which are typical diseases caused by hexavalent chromium. Diseases caused by chrome(VI) are of a seriousness such that they have become an object of public concern. For these reasons, the waste of brick made from chromite or chromium oxides is difficult to dispose when considering environmental problems and therefore, there is a strong demand for the development of brick which does not contain chrome, that is, "chrome-free brick".
Thus, the prime object of this invention is to provide chrome-free brick which does not contain chrome and exhibits superior resistance to structural spalling, corrosion and heat spalling although it does not contain chrome.